The present invention relates generally to a technique for managing resources in a Common Channel Signaling (CCS) network, and specifically to a method and apparatus for decentralizing the management of network resources to interface units within a signaling point.
Common Channel Signaling (CCS) provides a dedicated supervisory network for segregating signaling information from voice and data information in a telecommunications network. CCS was developed to meet the increased demands placed on the public telecommunications network by the growing market for voice, data, and information services. Previous signaling systems sent call setup and routing information over the same trunk circuit used for voice transmission. With CCS, a single out-of-band channel conveys signaling information relating to call setup, routing, and network management, among other things. Signaling System No. 7 (SS7), an international protocol standard for CCS communications, creates a universal format for communicating signaling information in a CCS network (CCS7).
CCS7 networks also provide numerous advanced features for telecommunications users. By enabling communication between processors in central offices, CCS7 permits on-line or external databases to be queried. This capability opens access to such features as network-wide automated calling card service, Advanced Intelligent Network-based residential and business services, Custom Local Area Signaling Services, and Virtual Private Networking. Other advantages provided by CCS7 include Calling Number/Name Delivery and Automatic Callback to work across an entire network rather than just between subscribers served by the same central office.
FIG. 1 illustrates a typical CCS7 network configuration with three key signaling points: a Service Switching Points (SSPs) 12; a Service Control Points (SCPs) 14; and a Signaling Transfer Point (STPs) 16. SSPs 12 are located at a central office to provide CCS 7 trunk signaling and the capability to query a database to determine call routing. SCPs 14 house databases with call routing information that SSPs and other network elements use to provide advanced services in a telecommunications network. STPs 16 route CCS7 messages between the signaling points and control access to the CCS7 network.
Unlike other nodes in a CCS7 network 10, STPs 16 do not generally act as a source or ultimate destination of CCS7 application messages. Instead they function as both a static and dynamic routing database that control access to, and direct call signaling between, a variety of CCS7 nodes and networks. STPs 16 monitor, maintain, and report different levels of information concerning the availability and unavailability of CCS7 nodes, routes, and services.
Signaling points such as STPs 16 support external resources in the CCS7 network 10, such as links, linksets, routes, routesets, and subsystem databases resident in other signaling points. Each signaling point relies on these resources to effectively transmit signaling information or to access appropriate sources of information within the CCS7 network 10.
Managing these resources by the signaling point must take place to ensure the continued and reliable availability of the resources. Generally, resource management by an STP 16 includes both network management and subsystem, or application, management. Through network management, the STP 16 ensures the integrity of individual signaling links by monitoring the links and accessing errors that occur on them.
Typically, network management separates into three categories: link management, traffic management, and route management. Link management checks for continued integrity of the links. Traffic management enables the signaling point to route traffic around failed links within a linkset. Route management addresses the accessibility of signaling points in a CCS7 network, and advises other signaling points in the network if one of the signaling points cannot be reached. Similarly, subsystem management focuses on the availability of an application or subsystem database within the CCS7 network. Overall, resource management by a signaling point requires persistent attention to the status of resources through monitoring and communication.
Conventional signaling points, such as STPs 16, include a central processor for controlling functions performed by the signaling point, as well as for managing resources in the CCS7 network. Interface units within the signaling point provide the immediate interface between the signaling point and the external CCS7 network 10. The interface units within a conventional signaling point typically gather management information and pass it to the central processor for consideration. For instance, if a subsystem database within an SCP stops responding, the central processor within the STP will take appropriate action to poll the SCP to derive the database's status. In the meantime, the central processor will, if possible, route relevant communications of the STP to an alternate SCP.
The conventional signaling points with centralized control of resource management have several drawbacks. For one, the central processor of the signaling point has numerous other processing functions to perform, so resource management adds an unnecessary burden to the processing capacity of the central processor. This drawback becomes especially acute as the number of network resources supported by a signaling point grows. Similarly, if several management conditions arise simultaneously, e.g. numerous resources experience problems, the central processor within a signaling point may become a bottleneck for managing the resources and may slow the responsiveness of the signaling point.
In light of the foregoing, a need exists for a signaling point and a method for managing communication with network resources that does not burden the central processor of the signaling point. A need also exists for a signaling point and a method for managing network resources that enables rapid response to a plurality of simultaneous network resource management conditions.